This project attempts to define influences of age on the male reproductive system, especially the production of male hormones (testosterone, dihydrotestosterone), the trophic hormones, LH and FSH, and the latters' responses to LH-RH. Correlations between hormone levels, hormone binding to plasma proteins and the interrelations of these factors with aging are being made in the longitudinal study subjects. BIBLIOGRAPHIC REFERENCE: Harman, S.M. Clinical Aspects of Aging of the Male Reproductive System. In Schneider, E. (Ed.): The Aging Reproductive System. New York, Raven Press, 1977, pp. 29-58.